The deal between Tishman Speyer Properties — the owner of Rockefeller Center and the Chrysler Building — and the Metropolitan Transportation Authority fell apart Thursday because of an impasse over zoning and the timing of payments. The deal was reached in March with much fanfare to redevelop the 26-acre railyards, considered one of the city's last, best building opportunities.

"The plan isn't dead by any means," said Bloomberg, who was in London to meet with Mayor Boris Johnson. "Hudson Yards is the most exciting opportunity New York has."

Bloomberg met in private Friday with the developer's lead negotiator Rob Speyer and his father, Jerry I. Speyer, who flew in from Italy. Details of the meeting at the mayor's London apartment were not discussed.

The mayor said before the meeting the city was committed to developing the area, which also includes an extension of the No. 7 subway line.

"It's going to get done," he said. "And the No. 7 line is going to get done. And it will be so far along before I leave office that nobody is going to be able to stop it."

Transportation authority officials agreed to meet with Tishman Speyer on Monday, but said the developer would have to alter some requests that they say change the economics of the deal.

"I'm not going in with an expectation," Gary Dellaverson, the authority's chief financial officer, told the New York Times when asked about Monday's meeting. "They've taken a position which I've articulated to them was quite clearly unacceptable. They've asked to meet, therefore I'm meeting with them."

The Speyers said in a written statement that they hope to complete the deal.

Negotiations broke down Thursday after Tishman Speyer sought to postpone making payments for part of the railyards until the other half was rezoned the way the developer wanted, the transit agency said. The rezoning would need approval of City Council in a process likely to take years.

Tishman Speyer won a five-month bidding war over some of the city's biggest developers for the rail yards on either side of 11th Avenue between 30th and 33rd Streets, offering just over $1 billion for a 99-year lease.

Bloomberg insisted from London Friday that there was still room to negotiate.

"My hope is that the state government, really the MTA in this case, can get together and solve the problems they have and that Tishman Speyer has, so that they can come together," the mayor said.

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